Polyvinyl butyral sheeting has long been used as an interlayer in safety glass laminates. These laminates are commonly used not only in architectural but in automotive applications, where they serve a dual function of protecting persons inside a car from being struck by flying objects from the outside and preventing the occupants from penetrating the windshield on impact after a sudden stop.
Particularly in automotive applications, the adhesion of the polyvinyl butyral sheeting to the glass components must be carefully controlled to provide a balance between maintaining the integrity of the windshield on impact and cushioning the impact through energy absorption. Many adhesion control agents have been used successfully in the past, but often exhibit a moisture sensitivity that can result in marked variation in the desired degree of adhesion of the glass to the interlayer. Accordingly, continuing effort has been directed toward the development of adhesion control agents for polyvinyl butyral sheeting which can be used satisfactorily over a broad range of process conditions.